I'm always quite wary of these heavily technology driven approaches to addressing the 21st century sustainability crisis. In my opinion, our best route is a gradual mindset shift (facilitated by the amazing global communication power granted by the internet) where people gradually realize that more happy life years can be gained from less consumption. When looking at energy, this mindset will make everything easier by requiring less energy and also increasing the willingness to pay for more expensive clean energy.
Even though this mindset shift is happening slowly at present, it certainly is happening. More and more people are realizing that their lives can be healthier, happier, more productive and less cluttered as they intelligently reduce material consumption. The obvious competitive advantage that this philosophy of more production and less consumption brings is also very attractive in the marketplace.
Naturally, this mindset shift is starting in the developed world. To some degree it is being forced upon people by the dynamics of the global economy (e.g. median US household income is back to levels last seen in 1995 and the gradual emergence of negative benchmark interest rates around the developed world is a clear indication that the future will actually be smaller than the present), but more and more people are starting to consciously and proactively make this transition.
Meanwhile, developing nations should be allowed to industrialize in the fastest possible way (e.g. the China coal model) in order to limit population growth and rapidly increase the level of awareness of the population. By the time they reach sufficiently developed levels, the example pathway to happiness and longevity set by the developed world should be much more evolved than today's consumerist paradigm.
Technology will undoubtedly play a major role, but I think the gradual evolution of global societal mindset (and the resulting reduction in per capita material consumption) will be more important.